---
id: "CVE-2026-114730"
kind: "vulnerability"
aliases: ["CVE-2026-114730"]
title: "Roundcube Webmail: SSRF filter bypass via NAT64 IPv6 addresses reaches internal hosts"
severity: "high"
cvss: 7.2
epss: 0.00312
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["other", "php", "roundcube", "self-hosted", "webmail"]
not_affected_if: ["patched-1.6.20-or-later", "patched-1.7.5-or-later"]
published_at: "2026-10-22T03:16:38+00:00"
first_seen_at: "2026-10-23T21:57:30+00:00"
updated_at: "2026-10-25T03:28:02+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-114730", "first_seen_at": "2026-10-23T21:57:30+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-114730", "first_seen_at": "2026-10-24T07:15:51+00:00"}]
---

# Roundcube Webmail: SSRF filter bypass via NAT64 IPv6 addresses reaches internal hosts

Roundcube's check for local URLs misses the NAT64 prefixes 64:ff9b::/96 and 64:ff9b:1::/48 and the unspecified address ::/128, so IPv6 URLs like http://[64:ff9b::7f00:1]/ pass. The server can then be made to request loopback, link-local and cloud metadata addresses.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Roundcube version: it is affected if it is `1.6.14` to `1.6.19`, or `1.7.0` to `1.7.4`.
- Confirm whether the installation is running the upstream commit “Fix SSRF filter (is_local_url()) bypass via NAT64 64:ff9b::/96”.

## Fix

- Upgrade the 1.6 line to `1.6.20` or later.
- Upgrade the 1.7 line to `1.7.5` or later.

## Timeline

- 2026-10-23T21:57:30+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-114730
- 2026-10-24T07:15:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-114730

## From the sources

Roundcube Webmail 1.6.14 before 1.6.20 and 1.7.0 before 1.7.5 is affected by a server-side request forgery filter bypass. The network blocklist used by rcube_utils::is_local_url() omitted the RFC 6052 NAT64 prefix 64:ff9b::/96, the RFC 8215 local-use NAT64 prefix 64:ff9b:1::/48 and the unspecified address ::/128, so URLs such as http://[64:ff9b::7f00:1]/ passed the filter and reached loopback, link-local and cloud metadata addresses. Upstream fixed this in the commit “Fix SSRF filter (is_local_url()) bypass via NAT64 64:ff9b::/96”.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_